Method of making insulating tape



C. MOSIER ETAL METHOD OF MAKING INSULATING TAPE June 9, 1942.

Filed Nov. 1, 1938 5 Sheets-Sheet l June 1942. c. MOSIER ETAL METHOD OFMAKING INSULATING TAPE 3 sheets-sheet 2 Filed Nov. 1, 1938 NQN NW Q QNJune 9, 1942. c, MQSIER ETAL 2,285,755

METHOD OF MAKING INSULATING TAPE Filed Nov. 1, 1938 3 Sheets-Sheet 3Patented June 9, 1942 2,285,755 METHOD OF MAKING INSULATING TAPE CarlMosier and John L. Mohun, Jr., Chicago, Ill.,

assignors to Union Asbestos & Rubber Company, a corporation of IllinoisApplication November 1, 1938, Serial No. 238,204

6 Claims.

The present invention relates to a method for making insulating tape,and is particularly concerned with insulating tape of the type having awoven sheath and insulating filler.

The present application is a continuation-inpart of our priorapplications, Serial Nos. 108,170, filed October 29, 1936, forInsulating tape and methods of making the same; and 199,752, filed April4, 1938, for Method and apparatus for making insulating tape.

One of the objects of the invention is the provision of an improvedinsulating tape and method of making the same, which includes astructure that is adapted to entrap air between the tape and the pipe indead air spaces, to increase the insulating value of the tape.

Another object of the invention is the provision of an improved fillerstructure which is adapted to be drawn into an insulating tape sheathwith greater facility by virtue of its improved structure, which givesit greater tensile strength, and which tends to cause the filler tocontract into a smaller space while the filler is being drawn into thesheath.

Another object of the invention is the provision of an improved methodof manufacturing insulating tape of the class described, by means ofwhich a more simple and effective insulating tape may be constructed.

Another object of the invention is the provision of an improved machinewhereby the insulating filler is adapted to be placed within apreviously constructed woven sheath.

Another object is the provision of an improved machine for use in makinginsulating tape which is adapted to draw the insulating filler into thetape in such manner as to insure the construction of a relatively flatcontinuous insulating tape of uniform insulating characteristics.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the three sheets of drawings:

Fig. 1 is a view in perspective of a machine for drawing an insulatingfiller into an insulating sheath, in the manufacture of the insulatingtape;

Fig. 2 is a top plan view of a portion of the machine of Fig. 1 showingadditional details of construction with the filler and sheath as theyappear at the beginning of the operation of drawing the filler into thesheath;

Fig. 3 is a diagrammatic fragmentary plan view of a portion of aninsulating filler constructed according to the present invention;

Fig. 4 is a fragmentary plan view of a portion .of the insulating sheathconstructed according to present invention;

Fig. 5 is a fragmentary view in perspective of an insulating tapeconstructed according to present invention, that side of the tape whichis to be adjacent to the article to be insulated uppermost.

Fig. 6 is an enlarged diagrammatic plan view of .the upper side of theinsulating sheath of Fig. 5 showing the details of its construction.

Referring to Fig. 5, the present insulating tape, which is indicated inits entirety by the numeral Ill, preferably comprises a woven insulatingsheath II, which is tubular in shape, and which is provided with aninsulating filler, indicated in its entirety by the numeral l2.

The filler preferably consists of a plurality of large loose and softrovings of asbestos fibers, the rovings being indicated by the numeralsl3, I4,

I5, l6 and I1.

These rovings may be made of relatively long fibers or short fibers, andin some cases other insulating fibers, such as vegetable or animalfibers, may be used. In the preferred embodiment of the invention therovings have very little or practically no tensile strength, although aslight amount of vegetable fibers may be included to increase thetensile strength of the rovings to facilitate handling of the rovingsduring the manufacture of the filler I2.

These rovings are preferably'so arranged that they overlap each other;that is, the rovings l6 and H are disposed over the crack between therovings l2 and I3 and I4 and I5 respectively. When the filler iscomplete, the rovings flatten out to an elongated structure, which maybe substantially rectangular in cross section.

The filler I2 also preferably includes at each edge an asbestos rope l8,l9, which comprises asbestos or other fibers tightly twisted together,for the purpose of giving the filler a greater tensile strength.

Referring to Fig. 3, the rovings I3 to ll may be secured together by aplurality of threads 20, 2| and others extending spirally around theassembly I2-.|1 in a left hand direction as viewed in Fig. 9, and by aplurality of other threads 22, 23, and others which extend spirallyaround the assembly l3-l9 in the oppsite or right hand direction. Thesespiral threads 20-23 and; others form a basket weave about the ravinesand ropes and hold the parts of the filler together. When the spirallyextending threads 26-23 are subjected to longitudinal tension with therest of the filler, they tend to cause the filler to contract into asmaller space so that it can be more readily inserted in its sheath.

The ropes l8, I9, give the filler a tensile strength which enables it tobe drawn into the sheath H in substantial lengths, such as, for example,fifty feet, more or less. In addition to the threads 26-23, otherlongitudinally extending threads 24, may be arranged at the edges of therovings to increase the tensile strength of the assembly. It should beunderstood that any number of rovings may be used, and rovings arepreferably used in the preferred form of the invention. In someembodiments of the invention, however, other forms of flat fillers ofless insulating value might be used with the improved sheath.

Referring to Fig. 5, this shows the outside of an improved form ofsheath or of a tape which has on its rear side, that is, the side whichis innermost to the pipe when the tape is spirally wound on a pipe, aplurality of insulating ropes or large threads 26 extendinglongitudinally of the sheath, and a plurality of relatively large threadformations 21 extending transversely of the sheath and intersecting thethread formations which extend longitudinally thereof.

This forms depressed rectangular spaces 26 between the thread formations26, 21, and the depressions 28 are adapted to entrap air between thesheath and the pipe when the sheath is spirally wound on a pipe or whenit is applied to any other surface. This. greatly increases theinsulating value of the sheath and causes this increase at a slightadditional cost, which is not proportionate to the increased value ofthe tape.

The structure of Fig. 5 may be accomplished in different ways, oneexample being the addition to the sheath of longitudinally andtransversely extending relatively large threads or ropes of asbestos.

In the embodiment of Fig. 1, however, additional longitudinallyextending large threads or ropes 29 have been used, located on the loweroutside of the sheath and equally spaced from each other. Referring toFig. 4 and Fig. 6, in this embodiment 30 indicates the weft threads and3| the warp threads. Every fourth weft thread extends over the largethread or rope 29 and binds it to the woven assembly. Thus, for

example, the large thread or rope 29 in Fig. 4 is secured by the weftthread 30 at the bottom, the woven thread 30 at the middle of thefigure, and left thread 30 at the top.

The weft threads 30 may be drawn so tightly in the weaving that theycause the portions 21 of the warp threads 3| to project outward abovethe rest of the surface of the weave. In other words, the threadportions 21 project outward substantially as much as the ropes 29. Thisgives the appearance of the sheath on that side a waflle-like formation,as shown in Fig. 5, the transverse ridges being formed by the outwardlyprojecting portions 27 of the warp threads 3|.

The arrangement of the weave may be seen in greater detail withreference to Fig. 4, in which the warp threads have been numbered l to23. The ropes or large threads 29 have been arranged in the figure ontop of the warp threads 3, 9, l5 and 2 I, and they are secured byengagement with the weft threads 30.

Referring to Figs. 1 and 2, these are diagrammatic illustrations of apart of the apparatus used in the manufacture of the insulating tapepreviously described. In- Fig. l, indicates a table top which may beslightly longer than the longest length of sheath which is intended tobe filled by one operation of drawing the filler into the tape; forexample, if the tape is to be made in fifty-foot lengths, the table maybe or 69 feet long, so as to leave suflicient space on the table forwork at each end of the tape.

The table 50 is provided at one end, the left end, in Fig. 1 with asheath-holding fixture 5| that may comprise an angle iron member 52,provided with a relatively flat tubular member 53. The horizontal flangeof the iron 52 is secured to the table 50 by a plurality of screws,bolts, or other fastening means, and the vertical flange of the iron 52carries the fiat or oval tubular member 53.

The tubular member 53 is constructed of metal and it is of sufficientsize, with respect to the sheath ll, so that the sheath H is rathertightly stretched when it is placed upon the tubular member 53, as shownin Fig. 1.

In order to insure the securement of the sheath l I on the tubularmember 53, the apparatus may be provided with a cord having a loop 56,embracing the sheath and tubular member 53, and drawn tight by means ofa slip knot 55, the end of the cord being tied to a, peg 56 in the table50.

The shape of the tubular member 53 in elevation approximates the shapeof a flat tubular sheath II, with which it is used. The tubular member53 is adapted to serve as a rigid and fixed eye for the end opening ofthe woven sheath II and also for securing the sheath II in place, whilethe filler I2 is drawn into the sheath.

The filler I2 may be as shown in Fig. 3 and may be provided in suitablelengths to correspond to the length of the sheath H, and is stored incoils in a suitable barrel 51.

It should be understood that the table 50 may be provided with anynumber of different apparatus, including the fixture 5| and themachinery for drawing filler into a multiplicity of sheaths at the sametime.

The apparatus for drawing the filler into the sheath is mounted at theright hand end of the table in Fig. 1, and it comprises a suitableelectric motor 58, provided with worm gearfor driving the gear wheel 59,which is mounted upon a horizontal shaft, 60. The shaft 60 is rotatablymounted in bearings carried by the brackets 6|, and it is provided withone or more drums, 62, may be located between the vertical guides Eachdrum 62 has secured to its periphery a tension member 65, which mayconsist of a length of flexible steel strap. The strap of spring steelis longer than the length of the table 50 so that it may extend, whenunwrapped from the drum, to a point beyond the fixture 5|, where it maybe secured to the filler l2. At its free end, the steel strap isprovided with a U-shaped metal member 66, secured thereto by rivets orother fastening means and having a loop for receiving a cord 61. Thecord 61 may have a slip knot formed in its opposite end and may belooped around the end ofthe filler l2 at 66.

In order to insure the wrapping of the strap 65 upon the relativelynarrow drum 62, additional guide members 69 and 10 are provided on eachside of the drum 62 for slidably engaging the edges of the strap 65 andconfining it to the drum 62. Any number of drums in 62 may be employedupon the same shaft 66, depending upon the size of the motor, the lengthof the sheath into which the filler is to be drawn, and

. the resistance encountered.

We have found it convenient to use a pair of drums on the same shaft andsame table, but it is not necessary to use both drums at the same time.The sheath is secured to the tubular member 53 at one end and is laidout on the table 50 in approximately a straight line and extendingtoward the drum 62. Each drum 62 is preferably loosely mounted on theshaft 60 and its connection to the shaft 60 is controlled by a clutch H,the clutch being actuatedby a lever12. The operation of the machine willbe apparent from the foregoing description.

The spring steel strap 65 is sufficiently still so that it can bethreaded or inserted into the sheath H, beginning at the right hand end13. natural shape of the strap is straight so that it will lie flatly onthe table and so that it can be pushed into the sheath ll until itemerges from the tubular member 53.

The operator may then grasp the cord 61 and place the loop 68 about theend of the filler l2. The loop 68 should not only embrace the rovingsl3-l8, but it should also embrace the ropes l8, l9 and embrace threads 2l-23 of the filler. The loop 68 should also be arranged as close to theend of the filler as it can, while also making a secure connectionbetween the cord 61 and the filler I2.

We find that one good way to accomplish this result is to double overthe end of the filler and arrange the loop 68, embracing the doubleportion of the filler. The head 14 of the filler is thus formed by adoubled or bent over portion, which is less apt to be disintegratedduring its passage through the sheath I I. The slip knot of the gord 61is adapted to compress this doubled head so that it does not form anobstruction to the drawing of the filler I2 into the sheath II.

The motor 58 may then be started andthe drum 62 will wind up the strap65 and draw the filler l2 into the sheath 1 I, until it emerges at theend 13. Thereafter the excess portions of filler l2 are cut off and'thesheath is detached from the tubular member 53. The filler is, of course,detached from the strap 65. Care must be taken during the drawing in ofthe filler to see that it lies fiat and does not become twisted and thesheath ll must, of course, be laid out flat without any twists.

The nature of the basket weave of the enclosing threads 21-23 is suchthat a tension on these threads tends to cause the filler to contract,whereby it may be more easily drawn into the sheath.

Our method of the manufacture of insulating tape may be outlined brieflyas follows:

The woven sheath is constructed as a unit and woven by a weaving machineinto tubular form, the threads being composedmainly of asbestos. In manycases a small percentage of cotton may be interwoven with the asbestosfor the purpose of increasing its tensile strength, and if desired, finemetal wires may also be included.

The filler 12 may be assembled as shown in Fig. 3 and embracing threads2 I-23, may be wrapped spirally in both directions about the filler andthe edge ropes l8 and 19. The filler is coiled in a barrel or othercontainer 51, so that it may be freely withdrawn from the container whenit is to be assembled with the sheath.

The sheath is cut into predetermined lengths and laid out flat upon thetable, one end of the The sheath being secured to a tubular member. Arelatively stiff tension member is threaded through the sheath from theopposite end until it emerges at the tubular member, whereupon thetension member is secured to one end of the filler; thereafter, thefiller is drawn into the sheath by meansof the tension member, the actof drawing this member, causing the embracing threads on the filler tocontract the filler into a smaller space for facilitating its entry intothe sheath. The filler .is carefully guided and fed into the tubularmember and sheath without twisting, so that it will lie flat within thesheath.

The excess of filler at each end'of the sheath is then cut off and theinsulating tape is then adapted to be used by being wrapped spirallyabout a pipe or other object.

In certain embodiments of the invention the sheath wi1l-be provided witha dead air space 28 OnFig. 5, bymeans of the longitudinally andtransversely extending ridges 26 and 21 which are formed in theoperation of the weaving of the sheath.

The side of the sheath, or the side opposite to the dead air spaces, I8,is also preferably pro- .vided witha waterproof covering which may beapplied by means of rollers, the lowermost of which dips into acontainer of waterproofing and impregnating compound, such as a compoundincluding a rubber latex and an evaporating solvent. The waterproofcompound preferably extends to the ends of the sheath and over the rearside of the sheath, that is, toward the uppermost side in Fig. 5, sothat the article which is 'waterproofed covers enough of the tape sothat the waterproofed edges may engage each other when the tape isspirally wrapped upon a pipe.

It will thus be observed that we have invented an improved machine foruse in the manufacture of insulating tape and improved methods ofmanufacture of insulating tape by means of which the tape may be coveredwith a previously woven asbestos sheath. It is not necessary to turn thesheath inside out to fill it according to the present methods, nor is itnecessary to stitch the edges of the sheath together after the fillerhas been placed in it, and the insulating tape is constructed with thepresent apparatus according to the present methods of substantiallyuniform heat insulating characteristics and may be manufactured morecheaply than the insulation of the prior art, having equivalentinsulating value.

While we have illustrated a preferred embodiment of our invention, manymodifications may be made without departing from the spirit of theinvention, and we do not wish to be limited to the precise details ofconstruction set forth, but desire to avail ourselves of all changeswithin the scope of the appended claims.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States, is:

1. The method of making insulating tape which comprises holding atubular fabric sheath of insulating material, assembling a plurality oflarge, loose, soft rovings of insulating material in overlappingrelation to form a filler for said sheath, with reinforcing ropesextending longitudinally of said filler, and drawing said filler intosaid sheath to form the tape.

2. The method of making insulating tape which comprises weaving atubular fabric sheath of threads comprising asbestos fibers, said sheathincluding warp and weft threads of substantially the same size and alsoincluding a plurality of warp threads of substantially larger size, thelatter larger warp threads being located in spaced relation to eachother on the outside of the sheath and extending longitudinally thereofand being secured thereto by a plurality of regularly spaced weftthreads, said latter predetermined weft threads being drawn more tightlythan the warp threads which they engage for the purpose of providingtransversely extending ridges on the same side of said sheath as saidlarger warp threads, placing said sheath upon a support and securing oneend to said support, threading a straight and resiliently bendabletension member through said sheath, securing said tension member to oneend of a filler and drawing said filler into said sheath by means ofsaid tension member.

3. The method of making insulating tape which comprises weaving atubular fabric sheath of threads comprising asbestos fibers, said sheathincluding warp and weft threads of substantially the same size and alsoincluding a plurality of warp threads of substantially larger size, thelatter larger warp threads being located in spaced relation to eachother on the outside of the sheath and extending longitudinally thereofand being secured thereto by a plurality of regularly spaced weftthreads, said latter predetermined weft threads being drawn more tightlythan the warp threads which they engage for the purpose of providingtransversely extending ridges on the same side of said sheath as saidlarger warp threads threading a straight and resiliently bendabletensioning member through said sheath and attaching it to said filler,and drawing a filler into said sheath.

4. The method of making insulating tape which comprises weaving atubular fabric sheath of threads comprising asbestos fibers, said sheathincluding warp and weft threads of substantially the same size and alsoincluding a plurality of warp threads of substantially larger size, thelatter larger warp threads being located in spaced relation to eachother on the outside of the sheath and extending longitudinally thereofand being secured thereto by a plurality of regularly spaced weftthreads, said latter predetermined weft threads being drawn more tightlythan the warp threads which they engage for the purpose of providingtransversely extending ridges on the same side of said sheath as saidlarger warp threads, assembling a filler comprising a plurality oflarge, loose, soft rovings with left hand and right hand spirallyextending threads, attaching a tension member to said filler, andsubjecting said filler to tension to contract the filler, while drawingthe filler into said sheath.

5. The method of making insulating tape which comprises weaving atubular fabric sheath of insulating material, said fabric sheath havinga plurality of longitudinally extending ropes interwoven therewith, saidropes being adapted to prevent the contraction of the sheath undertension, assembling the plurality of insulating fillers in overlappingrelation to form a composite filler for said sheath with reinforcingthreads extending spirally about said filler, tensioning said filler,

and reinforcing threads, whereby the filler is caused to contract, anddrawing said filler into said sheath to form the tape.

6. The method of making insulating tape which comprises weaving atubular fabric sheath of insulating material, said fabric sheath, havinga plurality of longitudinally extending ropes interwoven therewith, saidropes being adapted to prevent contraction of the sheath under tension,assembling a plurality of insulating filler members to form a compositefiller for said sheath with reinforcing threads extending spirally aboutsaid filler whereby the filler is caused to contract into smaller sizewhen subjected to tension, laying said sheath in a straight, line, andsecuring one end of said sheath to a fixed support, threading arelatively stiff, yet bendable and resilient, member through saidsheath, and attaching it to one end of said filler adjacent the securedend of said sheath and wrapping the other end of said tension memberspirally about a support to draw the tension member and filler throughsaid sheath and locate the filler in said sheath.

CARL MOSIER. JOHN L. MOI-IUN, JR.

